A passive array technology using antenna arrays including waveguide or horn apertures with waveguide feed networks are becoming an important communication tool because such antenna arrays exhibit low level of losses. These antenna arrays represent one of the most suited technologies for passive arrays because of the low level of losses they exhibit. Applications requiring a significant bandwidth may use feed networks of the corporate type in order to provide equal amplitude and phase to all the elements in the array. As the number of antenna elements increases, the waveguide feed networks become increasingly complex and space consuming This can be problematic in many environments (e.g., avionics) where space and/or weight are at a premium. In some cases, inter-element distance may be constrained by the feed network size, which may degrade antenna performance.
A common problem with this type of architecture is the occurrence of grating lobes in the radiation pattern of the array, which happens if the inter-element distance is too large. Indeed, the fact that rectangular waveguides occupy more lateral space than other types of transmission medium (e.g., microstrip, etc.) makes it difficult to bring the antenna elements sufficiently close to each other such that grating lobes are avoided. This limitation can be even more severe with dual-polarized arrays, where the feed network system handles two channels, for the two orthogonal polarizations. Current architectures of antenna arrays using waveguide or horn aperture elements makes it difficult to maintain a desired inter-element distance with a compact waveguide feed structure.